[vsnet-grb-info 9548] GRB 100727A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11019
SUBJECT: GRB 100727A: Swift/UVOT Upper Limits
DATE:    10/07/28 16:14:12 GMT
FROM:    Stephen Holland at USRA/NASA/GSFC/SSC  <Stephen.T.Holland at nasa.gov>

S. T. Holland (CRESST/GSFC/USRA) and
D. C. Morris (GWU/GSFC)
report on the behalf of the Swift UVOT team:

    The Swift/UVOT observed the field of GRB 100727A starting 47 s
after the BAT trigger (Morris, et al., 2010, GCN Circ. 10998).
Settled observations started at 65 s.  We do not find any new source,
relative to the DSS, USNO-B1.0, or 2MASS at the position of the XRT
afterglow (Osborne, et al. 2010, GCN Circ. 11000).  Preliminary
3-sigma upper limits for detecting a source in the finding charts, and
in the co-added images, using a 2.5 arcsecond radius circular
aperture, are

Filter      T_start    T_stop    Exp(s)      Mag
------------------------------------------------
white (fc)       65       215       147    >20.8
                856      1006       147    >21.2
    u (fc)      278       527       246    >20.5

    v           609    18,409      1414    >20.9
    b           533    24,918      1215    >21.7
    u           278    24,189      2335    >21.7
 uvw1           658    29,885      2289    >21.9
 uvm2           633    28,542      2390    >21.8
 uvw2           584    17,496      1415    >21.8
white            65      7075       805    >22.1
------------------------------------------------

The quoted upper limits have not been corrected for the expected
Galactic extinction along the line of sight corresponding to a
reddening of E_{B-V} = 0.05 mag (Schlegel, et al., 1998, ApJS, 500,
525).  All photometry is on the UVOT photometry system described in
Poole et al. (2008, MNRAS, 383, 627).